Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3991       1380 
1996         3581       1258 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40567      16838 
2001        41564      16208 
2002        32656      14599 
2003        61585      25523 
2004        48321      18535 
2005        86180      26483 
2006       111627      35649 
2007       205723      63036 
2008       126732      36045 
2009       103239      28998 
2010       119804      33249 
2011       179976      49766 
2012       167106      46240 
2013       259062      73548 
2014       644470     164371 
2015       748877     198751 
2016       575313     153550 
2017       613551     164110 
2018       406201     113831 
2019       934161     227975 
2020       696762     178882 
2021       905489     217083 
2022       674338     192904 
2023       613354     176568 
2024       159743      45787